1. Field of the Invention
The present invention relates to an optical apparatus such as an image-pickup apparatus having a so-called retractable type lens barrel and a lens apparatus which is attached to the image-pickup apparatus.
2. Description of the Related Art
An image-pickup apparatus such as a compact digital still camera is often equipped with a retractable type lens barrel, which is retracted in the main body of the image-pickup apparatus when the apparatus is not in use (in a power-off state).
In a conventional retractable type lens barrel, a cam ring is rotated about an optical axis by a single motor, thereby moving a movable barrel, which engages with a cam-groove portion formed in the cam ring, and a lens thereinside between a retracted position and a zoom range extending from the wide-angle end to the telephoto end (see e.g., Japanese Patent Laid-Open No. 2002-350706).
However, a configuration in which a cam ring drives both a movable barrel and a lens is unsuitable for reducing noise caused by lens driving (zooming). More specifically, an output from a motor is transmitted to the cam ring through a reduction gear train, and the load in driving the movable barrel and lens increases noise generated from the reduction gear train. Also, when the cam ring is rotated, sliding of the cam ring on a fixed barrel, which rotatably supports the cam ring on the inner circumference or outer circumference side of the cam ring, generates a sliding sound. The sliding sound also interferes with noise reduction.
Like video cameras, a digital still camera of recent years is equipped with a moving-image-pickup function. For this reason, suppression of noise generated in zooming during image pickup (image capturing) is becoming important also in a digital still camera including a retractable type lens barrel.
Further, when a plurality of lenses that are driven in an optical axis direction inside a movable barrel during zooming and they are driven by a cam ring that drives the movable barrel, the number of cam-groove portions provided in the optical axis direction needs to be increased, thus increasing the length of the cam ring in the optical axis direction. This leads to an increase in the size of the image-pickup apparatus.